I have a ASUS HD7770-2GD5 Radeon HD 7770 GHz Edition 2GB 128-bit GDDR5 PCI Express 3.0 x16 HDCP Ready And i would like it to pair with a SAPPHIRE 100358L Radeon HD 7770 GHz Edition 1GB 128-bit GDDR5 PCI Express 3.0 x16 CrossFireX Support Video Card
they have the same model and sockets but different memory what is better pairing it with 1gb or another 2gb?
Another 2gb. If paired with a one, in essence each card will only be able to use 1gb of their memory. When Crossfiring, it's always best to use 2 of the same cards, or at least 2 cards with the same specs.